For future communication technologies, it will be an important research subject to achieve a seamless handover of a terminal between 3rd Generation Partnership Project (3GPP) and non-3GPP access technologies.
Currently, as the two access technologies are different in aspects such as air interface, authentication, user plane establishment, and control plane entities of core networks of the two access technologies have no corresponding interface, a seamless handover of a terminal between the 3GPP and non-3GPP access technologies is a hard forward handover process, that is, an attachment process will be performed again when the terminal in an active state accesses a heterogeneous access network.
After the terminal is attached to an access network, the terminal may select a network anchor point for connection to an external packet data network (PDN); and an Internet protocol (IP) address used by the terminal will be assigned by the network anchor point or provided by the external PDN. In the 3GPP access technology, an entity in a network may obtain an address of the network anchor point by using an access point name (APN); and in the non-3GPP access technology, the terminal may obtain the address of the network anchor point during access authentication or obtain the address of the network anchor point from a domain name server (DNS) by using the APN obtained during the access authentication. Therefore, modes for obtaining an address of a network anchor point are different for different access technologies. As such, when the terminal is attached to a 3GPP network, the terminal may select a network anchor point, and obtain an address of the network anchor point. When the terminal in the active state moves from the 3GPP network to a non-3GPP network, a reattachment process may be triggered, and a PDN gateway (PDN GW) reselection process needs to be triggered. If the mode for obtaining an address of a network anchor point in the non-3GPP network is used, the obtained network anchor point may not be a network anchor point obtained in the 3GPP network, which causes a change in connection of a user IP level, resulting in data loss. Therefore, when the terminal is handed over between different access networks, it is essential to keep the network anchor point unchanged in order to maintain the service continuity.
In order to keep the network anchor point unchanged, those skilled in the art proposed a concept: storing an address of a network anchor point obtained in an access network to a network server; and obtaining the address of the network anchor point from the network server when the terminal is handed over from the access network to another access network. As such, no matter which network the terminal is handed over to, the same address of the network anchor point may be obtained, thus avoiding loss of user data.
However, currently, storing an address of a network anchor point to a network server is not feasible, nor is deleting an address of a network anchor point from a network server feasible.